Numerous medical procedures require the advancement and positioning of medical devices within body lumens. Intravascular catheters, in particular, are currently utilized in a wide variety of minimally invasive medical procedures. Generally, an intravascular catheter enables a physician to remotely perform a medical procedure by inserting the catheter into the vascular system of the patient at a location that is easily accessible, and thereafter, navigating the catheter to a desirable target site. Using this method, virtually any target site in a patient's vascular system may be remotely accessed, including the coronary, cerebral, and peripheral vasculature.
Typically, the catheter enters the patient's vasculature at a convenient location, such as a blood vessel in the neck or near the groin. Once the distal portion of the catheter has entered the patient's vascular system, the physician may urge the distal tip forward by applying longitudinal forces to the proximal portion of the catheter. For the catheter to effectively communicate these longitudinal forces, it is desirable that the catheter have a high level of pushability and kink resistance.
Frequently the path taken by a catheter through the vascular system is tortuous, requiring the catheter to change direction frequently. In some cases, it may even be necessary for the catheter to double back on itself. In order for the catheter to conform to a patient's tortuous vascular system, it is desirable that the intravascular catheter be very flexible, particularly in the distal portion.
While advancing the catheter through the tortuous path of the patient's vasculature, physicians often apply torsional forces to the proximal portion of the catheter to aid in steering the catheter. To facilitate the steering process, the distal portion of the catheter may include a plurality of bends or curves. Torsional forces applied on the proximal end must translate to the distal end to aid in steering. It is, therefore, desirable that the proximal portion of the intravascular catheter has a relatively high level of torqueability and rigidity to facilitate steering.
The distance between the access site and the target site is often in excess of 100 cm. The inside diameter of the vasculature at the access site is often less than 5 mm. In light of the geometry of the patient's body, it is desirable to combine the features of torqueability, pushability, and flexibility into a catheter that is relatively long and has a relatively small diameter.
The physical attributes that aid a physician in advancing the catheter through the tortuous path of the patient's vasculature also create packaging difficulties for the manufacturer. For a catheter to be used in the manner for which it is manufactured, the shape of the catheter must be maintained in its original form. Therefore, the proximal portion of the catheter body needs to be maintained in a generally straight alignment. The unique distal end formations, on the other hand, must be secured in the shape that the manufacturer originally imparts. As a result, a catheter's packaging is generally long and narrow.
Current packaging techniques for catheters generally include the use of a mounting card. Mounting cards are generally long, stiff cards having a plurality of die-cut tabs that hold the catheter in place. These die-cut tabs are usually created using a manual press that cuts the specific shape of the tab into the mounting card. Once the tabs are cut, the tabs are then raised, allowing the catheter to be woven under the tabs. The tabs are then lowered, allowing the catheter to be held in place by the tab's downward pressure. One in the art generally knows this weaving procedure as “webbing.”
Because the press physically cuts into the mounting card when forming the tab, residual foreign material is often released when the tabs are raised for the webbing process. This residual foreign material is commonly known as “angel hair.” It is desirable to minimize all foreign material when packaging medical devices. Current packaging standards, however, permit the presence of some foreign material.
Acceptable foreign material is generally smaller than five square millimeters in size and no more than three pieces are permitted per unit packaged. These small pieces of foreign material, however, are known to attach themselves to the packaged catheter. Complications are foreseeable from this contamination of the packaged catheter. For example, while inserting the catheter within a bodily pathway, the foreign material may also be introduced within the body.
Once the catheter is webbed onto the mounting card, the device is secured. The downward force exerted by the tabs prevents lateral and longitudinal movement of the catheter. Although this is quite beneficial in maintaining the catheter's desired shape and position within the packaging, it is less desirable with regards to the removal of the catheter from its packaging.
Physicians have found that catheters fastened by tabs often succumb to physical deformation during the catheter's removal. The tabs are so effective at securing the catheter that, even when the physician carefully removes the catheter, the catheter occasionally deforms. The deformation is particularly prevalent in the highly modified distal end region of the catheter. Because the distal end is generally the most flexible region of the catheter, the distal end may be deformed quite readily. Pulling the device through a tab may easily impart a new structural formation to the catheter that was not desired by the manufacturer. Thus, the manufacturer's precision in manufacturing the distal end region can be easily frustrated by the tabs.
A similar deformation issue associated with the removal of the catheter from tabs is kinking. Because the tabs are formed from the same rigid material as the mounting card, the tabs also possess a significant level of rigidity. This rigidity aids the tabs in securing the catheter under its downward pressure. When a physician, however, pulls on the catheter to free the device from the confines of the tab, a permanent kink or bend may be imparted to the catheter. Release of the catheter from the mounting card is generally achieved by force. Ideally, the tabs will yield to the force exerted upon the catheter and allow the catheter to be removed. In certain circumstances, however, it is the catheter that yields to the rigidity of the tab. The incidence of this occurring is particularly high when a physician pulls upon the catheter perpendicular to the mounting card while it is secured onto the mounting card. When pulled as such, the catheter yields to the tab and bends at a sharp angle near the edge of the tab. Catheters possessing such sharp bends lose much of their pushability strength because of the natural tendency to bend at these weakened points. This compromise in the catheter's configuration renders the catheter useless for its desired intention.
Webbing catheters onto their mounting cards is an arduous process. This process is made more difficult by the size and geometry of most catheters. As a result, automation of the webbing process has proven to be a daunting task.
The webbing process utilizes a flat plate press commonly known as a “webber.” The plate of the webber machine is slightly longer than the mounting card (approximately 40 inches long) and approximately six (6) inches deep. The webber is further described as having an upper and lower plate hinged at the back with a handle located in the middle front of the press. From a seated position, the assembler lifts the handle, requiring a lift and push force from the elbow and shoulder. The weight of the upper plate of the press weighs approximately 5 pounds. With an extended arm, however, the force required to lower and raise the plate equates to about 40 pounds. The assembler weaves the catheter onto the mounting card using a slight back and forth motion powered by the shoulder muscles. Currently, upwards of thirty (30) repetitions of arm movements (including raising and lowering the plate, weaving the catheter through the die-cut tabs, inserting and removing the cardboard) are completed every minute, assuming a cycle time of ten (10) seconds. The process thus has the potential for over-exertion and injury.